Science & Environment

Colorado's San Luis Valley revels every spring as 25,000 sandhill cranes hang out for a month at the Monte Vista National Wildlife Refuge — an established artificial haven where farmers place barley and federal wildlife managers pump water from underground aquifers to create the wetlands the birds need to gain energy for the migration north. (Lindsay Pierce, The Denver Post)

Colorado's effort to replenish its aquifers by cracking down on pumping groundwater threatens to leave the thousands of sandhill cranes that arrive here each February without the water they need.

"This certainly has the potential for changing the dynamics of what we have witnessed for the last 50 years," said Michael Blenden, federal manager of the San Luis Valley complex of three national wildlife refuges and the Sangre de Cristo Conservation Area.

The cranes will be fine this year, but rules are kicking in that would prevent federal wildlife managers from pumping the 2.67 billion gallons they typically draw to create artificial wetlands for migratory birds. Farmers also grow barley and lay it out to help sandhill cranes, which draw visitors from around the world.

The cranes — about 25,000 of them are amassing in the San Luis Valley this month — need the food and the protection the marsh provides.

But state officials have been working for years to control overpumping of the groundwater and prioritize who gets scarce water in a semiarid region.

They say the groundwater pumping must cease
unless federal officials obtain rights to surface water and leave it in rivers to offset their tapping of aquifers. If a trade can't be worked out, that could cost more than $1 million, Blenden said.

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"Just like every other groundwater user, the refuges will have to remedy the injurious stream depletions that occur due to their groundwater use," state natural resources spokesman Todd Hartman said.

State officials and refuge managers have discussed the impending requirements, which may also force tens of thousands of irrigated acres out of production. Farmers have formed cooperative districts to try to adapt.

Colorado's San Luis Valley revels every spring as 25,000 sandhill cranes hang out for a month at the Monte Vista National Wildlife Refuge, an established artificial haven where people place barley and pump water from aquifers to create the massive marshes the birds need to gain energy for their migration north. The cranes eat and gain strength for breeding in Idaho, Montana and Wyoming. A new Colorado rule limiting pumping of aquifer water in the San Luis Valley could endanger the habitat. (Lindsay Pierce, The Denver Post)

Scientists believe sandhill cranes in lesser numbers probably have migrated through the San Luis Valley for thousands of years. A petroglyph on the west side of the valley, depicting what appears to be a crane, may be 3,000 years old, according to federal officials.

The artificial wetlands has helped ensure the cranes' survival and now draw 95 percent of the cranes across a six-state region, federal biologist Scott Miller said.

Dried-up marshes would be less appealing and may not meet cranes' need to gain strength for their flight to nesting areas in Wyoming and Idaho and breeding there, Miller said. Cranes roost at night in wetlands, sleeping while standing in water. Coyotes or other predators are hampered as sloshing sounds can alert cranes.

"We don't want to put the state in a position of having some kind of confrontation with us. We are contributing to the groundwater problems, just as the agricultural community is," Blenden said.

Yet climate change creates new challenges, and preserving wildlife is part of a national mission, he said.

"We're relying more and more on habitats that we know are artificially created and maintained. We cannot just turn our backs, because things get a little rough, and let the cranes figure it out."

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